Current Output Too Low; Alarm Relays Don't Work; Bubbles Trapped Against Membrane; Simulating Inputs - Emerson Rosemount MCL-220 Manual

Troubleshooting
9.6.2

Current output too low

Load resistance is too high. Maximum load is 600 Ω.
9.6.3

Alarm relays don't work.

1.
2.
9.6.4

Bubbles trapped against membrane.

See Section
9.7

Simulating inputs

To check the performance of the transmitter, use a decade box and 1.5 V battery to
simulate the current from the sensor. The battery, which opposes the polarizing voltage, is
necessary to ensure that the sensor current has the correct sign.
1.
2.
3.
4.
74
Verify the relays are properly wired.
Verify the deadband is correctly configured.
9.5.5, step 4.
Disconnect the anode and cathode leads from terminals 8 and 10 on TB1 and
connect a decade box and 1.5 V battery as shown in
Figure 9-2: Simulating Chlorine
It is not necessary to disconnect the RTD leads.
Set the decade box to 2.4 MΩ.
Note the sensor current.
It should be about 500 nA. The actual value depends on the voltage of the battery.
To view the sensor current, go to the main display and press INFO. Choose sensor 1
information. The input current is the second line in the display.
Change the decade box resistance and verify that the correct current is shown.
Calculate current from the equation:
Figure 9-2.
Rosemount MCL